Our invention relates to a radio communication system, and particularly to an improved arrangement and method for establishing communication through a repeater between a first transmitter and receiver and a second transmitter and receiver over a radio frequency channel selected from a plurality of such channels.
In many localities, a plurality of land mobile radio frequency channels are allocated for communication between vehicles. Generally, there may be, and usually are, many more vehicles with radio transmitters and receivers than there are available radio frequency channels in a given locality. Consequently, some arrangement is needed for enabling a mobile vehicle user to obtain a radio frequency channel. As used in this application, radio frequency channel means at least a first radio frequency for transmitting and a second radio frequency for receiving.
Accordingly, a primary object of our invention is to provide a new and improved arrangement or method for detecting an idle radio frequency channel in a plurality of such channels, and enabling a transmitter and receiver on that idle channel for communication with another transmitter and receiver.
Another and fairly general object of our invention is to provide a new and improved arrangement or method for establishing radio communication between vehicles through a radio repeater.
Another object of our invention is to provide a new and improved arrangement or method for detecting an idle radio frequency channel, and enabling a transmitter and receiver on that idle channel for communication with another transmitter and receiver through an intermediate repeater.
Another object of our invention is to provide a new and improved communication establishing arrangement which can be placed in a transmit or call originate mode to enable an associated radio transmitter and receiver on an idle radio frequency channel, and to enable other transmitters and receivers in a selected or predetermined group on the same radio frequency channel.
Another object of our invention is to provide a new and improved communication establishing arrangement which can be placed in a receive or idle mode to cause an associated radio receiver to scan or search the available radio frequency channels and to enable the associated radio transmitter and receiver on the radio frequency channel having a tone indicative of a predetermined group.
Arrangements for establishing radio communication between vehicles have been provided, and are sometimes called trunking systems. However, such arrangements have been relatively complex and hence expensive, or have required a separate radio signalling channel for establishing communication between vehicles. Such a signalling channel is typically not available for voice communication, so that the utilization of the radio frequency spectrum is not as effective as might be desired.
Therefore, another object of our invention is to provide a new and improved arrangement that is relatively simple and hence inexpensive to establish radio communication between vehicles.
Another object of our invention is to provide a new and improved arrangement or method to establish radio communication between vehicles through a repeater without the need for a separate radio signalling channel.
Another object of our invention is to provide a new and improved mobile radio trunking arrangement that operates without the use of a common control terminal at or for the repeater, as required in some prior art trunking arrangements.